current divider rule

Discussion in 'Electronics Resources' started by sadaf, Sep 27, 2010.

  1. sadaf

    sadaf Thread Starter New Member

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    my question is:
    in cdr formula why don't we put the resistance in the numerator of that resistor across which we want to find out the current...

    Ia= (Rt*It)/(Ra)

    or in the special case of CDR

    Ia= (Rb*It)/(Ra+Rb)



    according to me, as current is inversely related with resistance so that's why.....................



    what do you think?give me your thoughts about this........?
  2. t_n_k

    t_n_k AAC Fanatic!

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    If you mean Rt=Ra+Rb then clearly you'll get the wrong result. Ia would exceed It - which would be unexpected to say the least!

    Your question isn't clear to me. What is the heart of the problem from your perspective?
  3. Ghar

    Ghar Active Member

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    Current is inversely related with resistance yes, but with current division you have two (or more) resistors in parallel rather than two (or more) resistors in series.

    The branch with 0 resistance would get 100% of the current.
    With a voltage divider if one resistance is 0 that resistance gets 0% of the voltage.

    It's an inverted situation, you swapped voltage and current as well as series and parallel.
  4. sadaf

    sadaf Thread Starter New Member

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    OK i understood......
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